1. Field of the Invention
This invention relates to a starting composition for the production of silicon carbide and a method of producing the same, and more particularly to a starting composition usable for the production of silicon carbide through a carbon reduction process. Further, it relates to a starting composition applicable for the production of very fine powder of silicon carbide and a method of producing the same.
2. Related Art Statement
Heretofore, the following methods have been known for the production of silicon carbide:
(1) method of carbonizing metal silicon powder with carbon powder or a hydrocarbon gas; PA1 (2) method of reduction carbonization of silicon oxide powder with carbon powder or a hydrocarbon gas; PA1 (3) method of reacting a halogenated silicon and a hydrocarbon gas at vapor phase; PA1 (4) method of precipitating silicon carbide from an organosilicon high molecular weight compound; PA1 (5) method of reacting silicon dioxide and carbon at a molten state; and PA1 (6) method of electrolyzing a molten salt. PA1 (a) mixing silicon dioxide powder with a high molecular weight organic compound to form a kneaded mixture; PA1 (b) heating the kneaded mixture to perform a carbonization reaction of said high molecular weight organic compound to thereby form a porous carbonaceous substance, and at the same time uniformly dispersing said silicon dioxide into a matrix formed by said carbonaceous substance to form a composite body; and PA1 (c) granulating said composite body into granules.
Among them, the inventors have particularly examined the methods (1)-(4) and confirmed the following. That is, in the methods (3) and (4), a very fine powder of silicon carbide can be produced, but the starting materials used are very expensive. In the method (1), it is difficult to obtain very fine silicon powder, as an industrial method. On the contrary, the method (2) is considered to be effective because relatively cheap starting materials can be used. In fact, the inventors have made studies with respect to the production of fine powder of silicon carbide based on the method (2) and have proposed various techniques using the same, such as in Published Japanese Patent Application No. 58-194,731, No. 59-39,709, No. 59-141,411 and No. 59-190,208.
All of the foregoing techniques are concerned with a method of using very fine carbon powder as a starting material and are to provide pellets of starting composition for the production of silicon carbide, wherein the carbon particle is uniformly arranged around the silicon dioxide powder for obtaining fine silicon carbide powder. Since the very fine carbon powder generally has an agglomerating property, however, it is difficult to uniformly disperse this powder, so that in the above techniques, it is very difficult to obtain pellets of the starting composition for the production of silicon carbide in which the carbon powder is uniformly dispersed around the silicon dioxide particles.